| 摘要 |
PURPOSE:To increase the accuracy of conduction control for a lattice control rectifying element, by detecting the width of zero cross detection pulse with a microcomputer and correcting the trigger phase for thyristors or the like in accordance with the width. CONSTITUTION:A power supply voltage which is stepped down so that the peak value is 15 volts, is full-wave-rectified at D0 and applied to a C-MOS buffer amplifier (inverter) IN1 via a resistor R2. With the 2.5 threshold level of the amplifier IN1 as a boundary, the upper part goes to L and the lower part goes to H, and a zero cross detection pulse (L level) is produced and the pulse width is about 400musec. This pulse is wave-shaped and inverted at a Schmitt circuit IN2 and inputted to an interruption terminal of a microcomputer MPU, and the pulse width detection is made by setting the fall as a start point. Thus, the load is controlled via a high speed switching circuit (not shown). |
